Electromagnetic radiation, especially in the frequency range of microwaves, is frequently used for electrosurgical or hyperthermia therapy in order to ablate or coagulate distinct targeted areas or volumes (especially lesions) of a biological tissue in order to treat various diseases.
In this respect, electromagnetic radiation can effectively heat a tissue especially in at least one of two ways, namely by inducing an electric current in the tissue (if it is electrically conductive), or by inducing a rotation of the dipoles present in water molecules in the tissue (dielectric heating), wherein the rotation of the dipoles changes with changes in the electromagnetic radiation so that due to internal friction in the tissue cells, each dipole becomes a heating source.
US 2010/0145328 discloses an electrosurgical ablation apparatus and a method of ablating biological tissue. The apparatus comprises a handheld microwave subassembly which generates and amplifies a microwave signal for treatment, and includes a treatment antenna for delivering the microwave signal in the form of microwave radiation into the targeted tissue. Further, the subassembly comprises diode detectors for detecting forward and reflected power levels to enable determination of net delivered power. A dynamic impedance matching system may be provided to match energy developed by the amplifiers in the subassembly to the biological tissue load.